If her hands are small, and I mean really small (like my fiancee's) don't even worry about double stacks. They won't fit right, and she'll never be comfortable with them. I've asked before, and people
think they know what I mean by small hands and they have no idea. I had a friend give her a bunch to try, and he was absolutely baffled by how small her hands were. My fiancee can't even hold a Glock 19 straight on and reach the trigger, she has to hold is cockeyed just to be able to reach the trigger, and hates it as a result.
So far, she likes the Sig P239 (with normal plastic grips, not wood ones) and the Kahr pistols. The P239 filled her hands nicely, and the Kahr even has a little space to spare. The Sig P225 was a little too big for her to be comfortable with. The 220, 226, 229, XD9, G19, M&P 9, and CZ-75 were all way to big for her. Top that off with the fact that since her hands are so small, heavy trigger pulls are out of the question as well. The best choices so far for her have been a Sig P239 w/ DAK trigger, or the Kahr for their nice DAO triggers. I have high hopes for a P250 with small frame and short trigger, but I certainly don't want to drop money on it just to find out.
Tiny hands certainly limit choices for pistols.